The Role Of MicroRNA-497 In The Development Of Breast Cancer And Its Regulation On MAPK/EPK Signaling Pathway

Objective:To further elucidate the pathogenesis of breast cancer and provide theoretical basis for the diagnosis and treatment of breast cancer,this study examined the expression level of microRNA-497 in breast cancer tissues and non-cancer tissues,and analyzed its relationship with proliferation and invasiveness of breast cancer cells in cell experiments,as well as the regulation of microRNA-497 on MAPK/ERK signaling pathway,so as to further explore microRNA.The role of microRNA-497 in the occurrence and development of breast cancer provides a theoretical basis for the diagnosis and treatment of breast cancer.Methods:From June 2017 to March 2018,158 cases of breast cancer were collected in the Hospital of traditional Chinese Medicine affiliated to Southwest Medical University as case group.At the same time,158non-breast cancer patients who were treated in breast surgery were collected as control group.The peripheral blood samples of the two groups were collected.We paired each patient with breast cancer tissue and adjacent normal tissue.Breast cancer cell line MCF-7,MDA-MB-468 and human normal breast cell MCF10 A were purchased from the Institute of Basic Medicine,Chinese Academy of Medical Sciences.Breast cancer MCF-7 cells and MDA-MB-468 cells were divided into three groups: Blank group(no plasmid transfection),NC group(Negative control,empty plasmid transfection),and MM group(microRNA-497 mimic plasmid transfection).The relative expression of microRNA497 in blood and cells was detected by RT-PCR.The expression levels of MAPK/ERK signal-related proteins(MAPK and Erk proteins)in cells and tissues were detected by Western blot.CCK8 assay was used to detect the proliferation of breast cancer cells.Transwell assay was used to detect cell invasiveness.Scratch test was used to detect the migration ability of cells.Results:1.The expression level of microRNA-497 in plasma of the case group was significantly lower than that of the control group(t=4.541,P=0.000),and the expression level of microRNA-497 in cancer tissue was significantly lower than that in para-cancer tissue(t=4.445,P=0.000).2.The expression level of plasma microRNA-497 was significantly lower in breast cancer patients with stage III+IV,metastasis,ER-positive and PR-positive.3.The area under curve,sensitivity and specificity of microRNA-497 in the diagnosis of breast cancer were 0.834,0.76 and 0.89,respectively.4.The expression level of p38 MAPK protein in cancer tissues was significantly higher than that in adjacent tissues(t=6.23,P=0.000),and the expression level of p-ERK protein in cancer tissues was significantly higher than that in adjacent tissues(t=7.770,P=0.000).5.There was a significant negative correlation between the expression level of microRNA-497 and p38 MAPK protein(correlation coefficient=-0.558,P=0.000);there was a significant negative correlation between microRNA-497 and the expression level of p-ERK protein(correlation coefficient=-0.392,P=0.005).6.The expression level of microRNA-497 inMCF-7 and MDA-MB-468 breast cancer cells was significantly lower than that in human normal breast cells MCF10A(P=0.000),and there was no significant difference in the expression level of microRNA-497 in MCF-7 and MDA-MB-468 breast cancer cells(P=0.539).7.In breast cancer MCF-7 cells and MDA-MB-468 cells,the expression level of microRNA-497 in microRNA-497 mimic group was significantly higher than that in Blank group and NC group.There was no significant difference in the expression level of microRNA-497 between Blank group and NC group.8.In MCF-7 cells and MDA-MB-468 cells,all kinds of intervention cells showed a proliferation trend.Cells in Blank group and NC group proliferated faster,while those in Mi-497 mic group proliferated slower.Mi-497 mimic group had significantly lower cell proliferation than Blank group and NC group.There was no significant difference in cell proliferation between Blank group and NC group.9.In MCF-7 cells and MDA-MB-468 cells,the number of perforating cells in the Mi-497 mimic group was significantly lower than that in the Blank group and NC group.There was no significant difference in the number of perforating cells between the Blank group and the NC group.10.In MCF-7cells and MDA-MB-468 cells,the migration distances of Mi-497 cells were significantly lower than those of Blank and NC groups.There was no significant difference between Blank and NC groups in migration distances.11.There were significant differences in the expression levels of p38 MAPK and p-ERK proteins in two types of breast cancer cells(MCF-7 andMDA-MB-468).The expression levels of p38 MAPK and p-ERK in microRNA-497 mimic group were significantly lower than those in Blank group and NC group.There was no significant difference in the expression levels of p38 MAPK and p-ERK between Blank group and NC group.Conclusion:The expression of microRNA-497 in serum,breast cancer tissues and breast cancer cells of breast cancer patients is decreased.Reduced levels of microRNA-497 in the population are closely related to the progression of breast cancer,and negatively related to the expression levels of MAPK and Erk proteins.miR-497 overexpression plasmid inhibits the proliferation,migration and invasion of breast cancer cells,and inhibits the expression of p38 MAPK and p-ERK proteins in MAPK/ERK signal.These results suggest that microRNA-497 may inhibit the progression of breast cancer by inhibiting the signal of MAPK/ERK.